1. Field of the Invention
The present invention relates generally to a keypad assembly with supplementary buttons and method for operating the same, and more particularly to a keypad assembly with supplementary buttons and method for operating the same, in which there are provided a supplementary mode switching button for switching the mode of a keypad and at least one supplementary selection-indication button for selecting and indicating one of a plurality of characters assigned to a single button in small-sized terminals (for example, miniaturized, portable, and mobile communication terminals), so that various characters, such as alphabet characters, numerals, and special characters, can be inputted with only a limited number of input buttons.
2. Description of the Prior Art
Generally, an input device of a terminal is used to interface a person with a mechanical device, and is closely related to a person. The terminal input device is included in electronic calculators, portable computers, mobile communication terminals, etc., and is closely connected with people's lives. Especially, the use demand for small-sized/portable communication terminals, which are convenient to carry, rapidly increases. An input method in terminals is a method for allowing a machine to recognize the thought of a man. An input device mostly utilizes a keypad (or keyboard) input method in which inputs are carried out through a person's contact with the input device. In such a keypad input device, a plurality of buttons are installed in a limited space to input characters, so it frequently happens that several characters must be inputted by one button. This is especially true of miniaturized/portable terminals of a very restricted size.
As shown in the construction view of a conventional miniaturized communication terminal of FIG. 1, since conventional small-sized terminals, such as mobile telephones and Personal Digital Assistants (PDAs), are restricted by their physical sizes, it is impossible to install many buttons in a keypad within an input device. Accordingly, it is difficult to construct the buttons of the input device. In most cases, it is only possible that the keypad has a few input buttons.
FIG. 1 shows a closed front view 110, a left side view 120, an opened front view 130, a right side view 140, and a back view 150 of an example of a conventional terminal, which is based on character input buttons 13 for representing numerals 0 to 9, alphabet characters A to Z, and special characters * and #, a plurality of function buttons 12, and other typical multiple functions. Further, referring to FIG. 1, reference numerals 11, 14 and 15 represent a display window, a microphone, and a keypad, respectively. Here, the terminal of FIG. 1 is typical, and unimportant functions from the viewpoint of the present invention are omitted.
For the portable terminals, since many buttons cannot be installed especially due to their restrictive sizes, mode switching operations are achieved by using the function buttons to input various characters, that is, numerals, alphabet characters and special characters. Moreover, even in a selected mode, inconvenient operations such as pressing the buttons as many times as the number of characters assigned to any one button are required.
Further, the conventional portable terminals are problematic in that an assigned character is recognized by the number of presses of a specific button, such that the keypad must wait some delay time between the pressing operations. The construction of the keypad and its operating method require the user to perfectly understand the functions of the keypad. Further, the construction of the keypad and its operating method cause the user confusion, are inconvenient in their manipulation, and cause the input speed to be decreased, due to the pressing of each button several times for each operation.
As an example for solving these problems, a keypad formed in a three-layer structure such that one key can perform two operations by constructing two contact points on the keypad is disclosed in Korean Patent Application No. 1995-48201. In this keypad, each key signal sensing means is formed in upper and lower portions using the three-layer structure, such that when the user presses the keypad, two or more functions can be executed through one key by controlling the intensity of pressure exerted on a key. In this case, the intensity of pressure exerted on a key can be well controlled with respect to such a keypad. However, if three or more characters exit on a single key button, three intensities of pressure must be distinguished from one another. Accordingly, character input errors may occur in the use of the keypad.
Further, a keypad configuration produced to improve the accuracy in pressing keys by enhancing the height of a key, reducing the surface area of the key and increasing the space between keys is disclosed in Korean Patent Application No. 1997-11506. This keypad configuration prevents a user from pressing more than one key at a time, provides space for alphabet characters beside each push button, and illuminates them, thus improving the visibility for characters and numerals. However, this keypad configuration only provides the convenience for pressing keys, while not providing convenience for mode switching of characters or numerals and their input processes when a user inputs a variety of characters or numerals.
An example of an apparatus and method for selecting and inputting characters is disclosed in Japanese Patent No. 1998-315522. The Japanese Patent discloses an apparatus and method for assigning similar character and symbol groups to a plurality of preset specific positions in the inspection table of a plurality of characters and symbols composing a software and a keyboard, displaying the inspection list of assigned similar character and symbol groups when one key position of any one group at the specific positions is selected and indicated, and selecting one character or symbol of them to be inputted. The apparatus and method must display the inspection table of characters and symbols to be inputted, and the similar character and symbol group inspection list based on the selection-indication. Therefore, the apparatus and method has limitation on application to small-sized terminals. Further, in the apparatus and method, characters represented on the keypad itself are not selected and inputted, but the character and symbol groups displayed on a display window are inputted by selection-indication of a selection-indication means.